Time-controlled electrical switches are in widespread use. Such time switches may be used to selectively and controllably enable and disable electrical conduction paths of diverse natures, including conduction paths transmitting communication signals. Such switches are most often used, however, to selectively enable and disable the application of power, typically A.C. power but potentially D.C. power, from a power source to a load. In this application, time switches may be used to selectively energize and de-energize loads periodically, from time to time, and/or at certain times of certain days. Energization of loads such as electrical lights and electrical machinery at selected times for selected periods is often appropriate to the intended use of such loads, the intended duty cycle of such loads, and/or the energization of the loads during non-peak electrical usage periods in order to reduce the cost of purchased power.
Electrically and electronically timed electrical switch systems are known in the prior art. These systems generally, however, suffer from certain limitations. Typically, customized timers of specialized capabilities are required for diverse applications. Particularly, timers of the 24-hour type, the 7-day type, with and without ability to skip control functions on a certain day or days, and the 24-hour diurnal astronomical event type (e.g. sunrise and sunset) are variously required.
Meanwhile, the electrical switching function that is desired to be performed by timed electrical switch systems is also variable. Particularly, the single pole single throw (SPST) switch function ranging to the multiple pole single throw (MPST) switch function, and the double pole double throw (DPDT) switch function are each, in various applications, desired to be performed. The proliferation of both specialized timers and specialized switching functions controllable by such timers has resulted in a large proliferation of common, National Electrical Manufacturers Association-recognized, timed electrical switches. For example, some electrical supply organizations stock numerous different timed electrical switches. It would be desirable if inventory carrying costs could be reduced by some form of modular timer system that accorded diverse, semi-custom, timing and switching functions by the convenient assembly of a limited number of modular components.
The electrical and electronic timer switches of the prior art that were generally designed and used for a particular application have generally not exhibited a uniform electrical connection. In particular, each one of a great number of individual switch units in the prior art was normally packaged with supportive documentation concerning its particular and often unique connection in an electrical circuit to variously individually function as an SPST, DPST, or DPDT switch. The prior art units did exhibit indicia near their terminal blocks or other electrical connection areas to aid the electrician in their installation. However, because the units were substantially non-standard, it was difficult for the electrician installer to learn, and remember, any uniform procedure of electrically connecting the different units even when some originated from the same manufacturer. Accordingly, if all SPST to MPST switches, and all DPDT switches were to each be connectable in a uniform manner, the efficiency of switch installation would be improved while the propensity for dangerous and fire-inducing miswires would be reduced.
The electrical and electronic switches of the prior art that were generally designed and used for a particular application have also generally not exhibited an advanced, user-friendly, interface. A user interface is required in a timer switch for its initial setup including time-of-day in a particular control application, and for subsequent programming of the timer unit with event time information for use in control of the timed electrical switch function. The difficulty of programming, and reprogramming, control sequences within prior art electrical and electronic timer switches has often caused the initial setup, and revision(s), of the time sequenced control within these timer switches to be a laborious task requiring considerable skill to perform. For example, prior art electrical switches often use pins or other electrical contacts which had to be laboriously positioned by the person programming the time control sequence of the timer switch unit. This task is often intricate and performed within small dimensions. This task must also be performed in poorly-lit or environmentally hostile conditions, and is not readily subject to verification.
An example of user-friendly interfaces for the control of a programmable timer unit are those user interfaces presented by electronic timers normally associated with videocassette recorders and televisions. The timer control section of these high-cost electronic appliances is primarily directed to permitting the user to program such appliances for the selective viewing and recording of television broadcasts.
The user interfaces of VCR's and televisions have improved in sophistication from certain early user control interfaces which were quite intricate in the required sequence of data insertion, difficult for the consumer-user to understand or memorize, and incapable of allowing the user to easily verify that the desired time control sequence had indeed been entered. Certain more sophisticated modern units operate on a request-response basis with the user. Current user-entered timer control information is consistently displayed in an intelligible manner, sometimes by an expanded alphanumerics display upon the television screen. The prior art userfriendly timed event programming procedures that are appropriate to VCRs and televisions are not, however, appropriate in many respects to the desired programming, and reprogramming, of an electronic timer switch unit.
This is because the programmed control of timer switch units, while preferably user-friendly, cannot be generally be so extremely sophisticated that the cost of the user-friendly programmable interface vastly exceeds the cost of the rest of the timer switch. This cost problem would, however, be mitigated to some extent in a system that provided a number of different timer modules, of varying programmable sophistication and functionality, which could be selectively used in timer switch systems as required.
Additionally differentiating the programmable control of an electronic timer switch from the prior art control of a VCR or television is a requirement that the switch, in response to a manually initiated signal be able to override a preprogrammed condition without the necessity of changing the installed program. Finally, electronic timer switches may be required to control events based on diurnal occurrences such as sunrise and sunset. This variable, diurnal, occurrence of timed events is not used for control of timers that are programmable only to capture television signals at set times for set durations on set days. When prior art electronic timer switches have performed switching based on periods of light and darkness, this switching has normally been controlled by photo cells or other sensors of the light. These photo cells generated control signals that were additive with other, timed, control signals originating within the timer switch unit.